Developments are currently being undertaken to develop applications, such as medical tests, chemical or biological analyses or synthesis operations, in microfluidic systems also denoted labs-on-chips.
These labs-on-chips are composed of a hydrophobic plastic, such as COC (cyclic olefin copolymer), COP (cyclic olefin polymer) and more generally poly(cycloolefins), PMMA (polymethyl methacrylate) and more generally acrylic polymers, polycarbonate, polyesters, silicones, certain polyurethanes and more generally any kind of resin, polymerizable under cold conditions or under hot conditions, of thermoformable materials.
The materials of COC type, for example, are not very dense, are very transparent, are biocompatible, have a thermal resistance up to 170° C. and have good resistance to chemicals.
However, their hydrophobic nature results in some disadvantages, such as interactions with some biological molecules, such as proteins, organic molecules, such as colorants, labels, drugs or any other type of molecule which it might be desired to study or prepare in such labs-on-chips, but also with micro- or nanoparticles which are often used as interaction support in these labs-on-chips. In order to overcome this disadvantage, the surface of the material is treated with an appropriate polymer which can, as the case may be, be neutral or be cationic, anionic or ampholytic in nature.
The French patent application published under the number 2 810 905 discloses an amphiphilic comb copolymer composed of a main backbone of poly(N,N-dimethyl-acrylamide) and of poly(methyl methacrylate) grafts. These hydrophobic units are adsorbed on the material of COC type and the poly(N,N-dimethylacrylamide) backbone gives a hydrophilic nature to the surface of the material.
In point of fact, the industrial synthesis of such a copolymer is difficult as it involves the preparation of a methyl methacrylate macromer and the copolymerization in solvent phases with purification stages.
Furthermore, as from the viewpoint of the development of the technique of the labs-on-chips for immobilizing cells, it may be necessary to render the hydrophobic surface slightly cationic.